1. Field of the Invention
This invention relates to a liquid jet recording apparatus which discharges liquid from a discharge port to form flying liquid droplets and effects recording by the use of the liquid droplets.
2. Description of the Prior Art
Non-impact recording methods have recently particularly attracted attention because the noise they generate during recording is negligible. Among methods ink jet recording (a liquid jet recording method), which is capable of high-speed recording and can effect full color recording without requiring the special process of fixing images on plain paper, is a very effective recording method and various systems of this method have heretofore been proposed, some of which have already been commercialized and some which are still being studied.
Such liquid jet recording methods comprise causing droplets of recording liquid (called ink) to fly and adhere to a recording medium to thereby accomplish recording, and are divided broadly into several types depending on the method of forming droplets of recording liquid and the method of controlling the direction in which the droplets fly.
Among those methods, the liquid jet recording methods disclosed, for example, in U.S. Pat. No. 3,683,212, U.S. Pat. No. 3,747,120 and U.S. Pat. No. 3,946,398 are so-called drop-on-demand recording methods which comprise causing liquid droplets to be discharged and fly from discharge orifices in response to a recording signal and causing the droplets to adhere to the surface of a recording medium to thereby accomplish recording. In this recording method, only the droplets necessary for recording are discharged, and this leads to the elimination of the necessity of installing special means for collecting and processing the discharged liquid unnecessary for recording, which in turn leads to the possibility of simplifying the apparatus itself or making the apparatus compact. This currently attracts attention because the direction of flight of the droplets discharged from the discharge orifices need not be controlled and that multicolor recording can be easily accomplished.
Also, a liquid jet recording method quite different in the principle of formation of flying droplets from the above-described liquid jet recording method is disclosed in Japanese Laid-open Patent Application No. 51837/1979. This liquid jet recording method is not only very effectively applicable to the aforementioned drop-on-demand recording method, but also can easily embody a recording head having a highly dense multiorifice configuration and therefore has a feature that recorded images of high resolution and high quality can be obtained at a high speed.
The liquid jet recording apparatus used in these drop-on-demand recording methods generally includes a recording head provided with discharge ports (orifices) for discharging liquid droplets, liquid flow paths communicating with the respective orifices and having energy generating elements for forming flying droplets, and a liquid chamber communicating with the liquid flow paths and storing therein the liquid to be supplied to the liquid flow paths. These elements are fixed to a head mounting portion which is a part of the liquid jet recording apparatus.
Also, the recording head is generally small and therefore, the amount of recording liquid which can be stored in said liquid chamber can only accomplish recording for a very short time. Accordingly, the liquid chamber of the recording head is usually connected to liquid supply means having as a part thereof an ink tank for storing therein the liquid to be supplied to the liquid chamber.
Heretofore, in the apparatus of this type, as a method of fixing the recording head to the head mounting portion, it has been popular to pass fixing screws through through-holes formed in the recording head and fasten them to internally threaded holes formed in the head mounting portion, or to fasten the head by fixing screws in a similar manner through a head fixing keep plate. Also, as a method of connecting the liquid chamber of the recording head to the liquid supply means, it has been popular to connect a tubular member provided on the recording head to a flexible tube provided in the liquid supply means by fitting the latter to the former. However, the recording head is generally small and therefore, the mechanism for fixing the recording head to the head mounting portion and the mechanism for connecting the recording head to the liquid supply means are very small and these two mechanisms are disposed proximate to each other. Thus, according to the above-described method using the screw setting or the fitting of the tube, the mounting and dismounting of the recording head with respect to the head mounting portion and the connection and disconnection of the recording head to and from the liquid supply means has been very inconvenient. Therefore, the work of interchanging the recording head resulting from a trouble such as the clogging of the recording head cannot be carried out by the user and a serviceman must be called for such work. And, even if a serviceman is resorted to, the inconvenience of such an arrangement has been a problem. Such disadvantage has been greater in a droplet jet apparatus having a plurality of recording heads mounted as in a liquid jet recording apparatus for effecting multicolor recording, because the space between adjacent heads is small.
Among the parts of a liquid jet recording apparatus, the part of the lowest reliability is the recording head for the present and, where the commercial planning of liquid jet recording apparatuses is to be made, sufficient provision of the service system for interchange of recording heads is necessary as a premise, and this point has also been a great bottleneck against commercialization.
Such a problem is common not only to the above-described drop-on-demand type liquid jet recording apparatuses using heat energy generating elements, but also to other drop-on-demand type liquid jet recording apparatuses using electro-mechanical converting elements and further the so-called continuous type liquid jet recording apparatuses.